| Standard | Description |
|---|---|
| Level 1: | Correlation between a crime prevention program and a measure of crime or crime risk factors at a single point in time. |
| Level 2: | Temporal sequence between the program and the crime or risk outcome clearly observed, or the presence of a comparison group without demonstrated comparability to the treatment group. |
| Level 3: | A comparison between two or more comparable units of analysis, one with and one without the program. |
| Level 4: | Comparison between multiple units with and without the program, controlling for other factors, or using comparison units that evidence only minor differences. |
| Level 5: | Random assignment and analysis of comparable units to program and comparison groups. |
(Sherman et al., 1997; Farrington, 2002)
“Directed police patrols at high crime bus stops between 12-1900 hours will reduce crime levels compared to bus stops with no police presence.”
The presence of police officers will increase the perceived risk of apprehension and therefore reduce offending.
| Measure | Description |
|---|---|
| Driver Incident Reports | Calls made by bus drivers to CentreComm, the London Buses control room, who determine whether an emergency response is required |
| Bus-related CRIS | A subset of Metropolitan Police recorded crime extracted using a keyword search |
A prospective power analysis was conducted to determine an adequate sample size for the study. Given a sample size of 102, an alpha level of .05 and a medium effect size (d = 0.5), the estimated power was 0.80.
| Risk | Mitigation |
|---|---|
| Non-equivalence between groups | Ran baseline comparisons (t-tests) |
| Attrition | Pair would be swapped out |
| Contamination | Conducted tests for presence of spatial autocorrelation |
| Senior police officers were not advised of the location of control sites |
Used adjusted Poisson-regression models to compare differences in pre- and post-treatment measures of outcomes and estimated-marginal-means.
| Buffer size | DIRs (% change) | Crimes (% change) |
|---|---|---|
| 0-50m | -37 | 25 |
| 50-100m | -40 | 23 |
| 100-150m | -10 | 7 |
Hotspots policing at bus stops - and potentially other “micro places” - has a limited deterrent effect if patrol patterns are predictable. Police agencies therefore need to randomise their deployments both spatially and temporally to increase the unpredictability of enforcement.
Ariel, B., & Partridge, H. (2016). Predictable Policing: Measuring the Crime Control Benefits of Hotspots Policing at Bus Stops. Journal of Quantitative Criminology.